Communication systems with over-the-air-programming or reprogramming of system information are known in the art. Such systems quite often reprogram information such as talk groups that are used within communications. The reprogramming information usually includes information that will be used to identify which communication units of the communication system are to be reprogrammed within the system. Quite often this information is the individual identification (ID) that programmed within each radio unit. When it is desired to reprogram, for example a talk group within a communication unit, the units individual ID is transmitted as part of a message including the new talk group that will be reprogrammed into the communication unit. Such a method is very convenient and time efficient, because information transmitted in such a message quite often takes milliseconds to arrive to the communication unit, whereas if the communication unit must be brought in for such reprogramming, that process may take hours, days, and even weeks, depending on the back up of programming at the particular site.
One drawback of over-the-air reprogramming, however, is that such information may be received by any communication unit that can receive information on that channel. Consequently, information that is reprogrammed over the air may be stolen and used in unauthorized units for various dishonest endeavors including eavesdropping and using of communication resources without paying for them. As a result, sensitive information such as unit identification codes and security codes are not reprogrammed over-the-air unless they are encrypted in some fashion. Various forms of encryption of RF signals exist, although adding such a feature to a communication unit is quite expensive, particularly if more than a minimal amount of security is desired.
When unauthorized communication units are accessing a communication system, the efficiency of such systems decreases because of the additional communication traffic added to the system. The amount of additional traffic is indeterminable for obvious reasons, and thus it is difficult to make adjustments to help correct for the situation. Thus, authorized users suffer in slower throughput of their communication requests as a result of unauthorized use of the system.
Accordingly, there is a need for a method of reprogramming information over RF channels such that information may not be easily intercepted for unauthorized use.